This disclosure relates to improved intraocular lenses for implantation in the eye and improved methods of anterior-posterior orientation. Embodiments of the improved intraocular lenses have at least one haptic support member that exhibits an improved visual guide to anterior-posterior orientation through use of improved coloration, patterning, or texturing.
Intraocular lenses (IOLs) are positioned in the anterior chamber, at the iris plane, in the ciliary suclus space, in the posterior chamber, in the capsular bag or other intended spaces inside the eye. Such lenses may be used in a variety of surgical procedures which include, but are not limited to, cataract surgery, clear lensectomy/vision correction, secondary implantation of an intraocular lens, phakic intraocular lens, and other vision correcting procedures.
It is preferable that intraocular lenses be implanted with the correct anterior-posterior orientation in order for the lens optics to achieve the desired optical result and so that the intraocular lens will have the correct position and desired movement, if so designed, inside the eye. Many modern intraocular lenses have advanced optical qualities, such as asymmetrical anterior and posterior optics, which may require proper orientation inside the eye in order to achieve the desired and intended visual results.
Many intraocular lenses also exhibit unique geometry of the haptic in relation to the optic, commonly known as haptic angulation, which may employ a preferred anterior-posterior orientation of the intraocular lens to achieve not only the desired visual result but also to discourage unwanted and potentially harmful interaction of the intraocular lens with ocular tissue, such as the cornea, iris, ciliary body, and lens capsule.
In some cases, an interaction with ocular tissue may be desired, such as the case when positive angulation of the haptics is used to position the IOL against the posterior capsule to attempt to prevent the inward growth of epithelial cells that may lead to a secondary cataract. If such an intraocular lens is implanted in the reverse orientation, upside down, this design intention may not be realized. In such a case, there is the potential for unwanted and potentially harmful interactions between the intraocular lens and iris or ciliary body.
There are also a growing number of intraocular lenses which are designed to move inside the eye, which may provide additional optical benefits such as accommodation and enhanced voluntary focusing of vision. These intraocular lenses frequently feature haptics with more complex shapes and angulations in order to attempt to produce desired movement of the lens optic. If these intraocular lens are positioned incorrectly, the resulting movement of the intraocular lens may be abnormal or reversed and may create optical problems and possible tissue interaction problems.
Currently, intraocular lens manufacturers address the issue of intraocular lens orientation by using design features, such as holes, notches, and tabs, to signal the proper orientation of the intraocular lens. However, these design features may be difficult to see and use for several reasons.
First, the design features used to identify the orientation of the intraocular lens, by their very nature, may be very small and difficult to see. Next, the intraocular lens is typically made out of a highly transparent and colorless material, making these subtle features even more difficult to discern. When the lens is folded and rolled-up in the injector, these design features cannot be identified or used to determine whether the intraocular lens is oriented correctly. When the lens is unfolded in an eye with a small pupil, it is frequently difficult or impossible to see the orientation notch, hole or tab, which may be hidden behind the iris. Furthermore, these design orientation features vary from lens model to lens model, increasing the potential for confusion.
When the intraocular lens is oriented incorrectly, the intraocular lens may unfold upside down inside the eye. In such a case, the orientation may be corrected, for example, by inserting micro-scissors inside the eye, cutting the intraocular lens into pieces, and then extracting the lens pieces. Surgical trauma may occur in the form of iris tears, intraocular bleeding, endothelial corneal damage, and rupture of lens capsule and/or zonules.
In the U.S., haptics may presently be colored using one or more of the three pigments that the FDA has approved for use: copper phthalocyanine, D&C (Drug and Cosmetic) Green No. 6 (IUPAC name: 1,4-bis(4-methylanilino)antracene-9,10-dione), and D&C Violet No. 2 (1-hydroxy-4-[(4-methylphenyl)amino]-9,10-anthracenedione). However, creating a strong and high contrast color difference using these pigments can be difficult. Copper phthalocyanine and D&C green No. 6 both have similar blue colors, while D&C Violet No. 2 has a violet color that does not strikingly contrast with the other two blue colors. Because haptics are typically transparent and thin, the difficulty in recognizing the differences among these colors is exacerbated when these colorants are used in haptics.